1. Field of the Invention
The present invention relates to a front passenger seat airbag apparatus that includes an airbag which is accommodated in a folded state in an accommodating portion disposed in an instrument panel in front of a front passenger seat of a vehicle, and an inflator which supplies inflation gas to the airbag.
2. Description of Related Art
In the related art, there is a front passenger seat airbag apparatus with a configuration disclosed in JP-A-2007-161089. The front passenger seat airbag apparatus of the related art includes an airbag into which inflation gas discharged from an inflator flows, and thus which is deployed and inflated so as to protrude from an accommodating portion toward a rear side of a vehicle. A membrane is disposed in the airbag to partition an inner region of the airbag in a front and rear direction into a front chamber and a rear chamber at complete inflation of the airbag. A vent hole is provided in the membrane for communication between the front chamber and the rear chamber.
In the front passenger seat airbag apparatus of the related art, the membrane partitions the inside of the airbag in the front and rear direction so as to inflate the front chamber firstly. However, the vent hole formed in the membrane is formed by cutting out a part of the membrane, and the vent hole is open all the time. For this reason, a flow rate of the inflation gas flowing from the front chamber into the rear chamber via the vent hole is substantially constant from initial inflation to complete inflation of the airbag. As a result, when an opening area of the vent hole is small, the front chamber can be quickly inflated. However, the inflation of the rear chamber is delayed compared to the front chamber, and thus an occupant is not protected immediately. In contrast, when the opening area of the vent hole is large, the inflation gas is not prevented from flowing into the rear chamber via the vent hole at the substantially same time when the inflation of the front chamber starts. For this reason, in a case where the opening area of the vent hole is large, when the inflation gas flows into the rear chamber, the entire airbag is deployed to greatly protrude toward the occupant, and thus the entire airbag oscillates considerably in the front and rear direction. Accordingly, there is room for improvement in the way that the inflation of the airbag is completed so as to be able to immediately protect the occupant.